PART 3.] 
Ball: Building and Ornamental Slones of India, 
105- 
In the city of Bombay trap has been used to some extent, but chiefly in rubble masonry. 
All the finer buildings in Bombay are constructed of a very different material, as will be 
mentioned in its proper place. 
The principal use to which the trap rocks of the Rajmehal Hills are at present put is for 
the supply of Calcutta with road metal. 
References. 
Building materials, Bombay Island, Carter’s Geology of Western India, Bombay, 1857, p. 161. 
Building stone in Western India, Merewether, Prof. Papers of Ind. Eng., Roorkee, Vol. VI, 1859, p. 130. 
Geology of Bombay Island, Wynne, Mem. Geol. Surv., Ind., V, 1884, p. 173. 
Geology of Western India, Blanford, Mem. Geol. Surv., Ind., VI, 1869, p. 379. 
Masonry in a trap country, H. Bell, Prof. Papers of lad. Eng., Roorkee, Vol. I, 2nd Series,. 1871, p. 162. 
III.— Serpentine. 
Serpentine in sufficient quantity to be deserving of mention in this enumeration is of 
rare occurrence in India. In the sub-metamorphic rocks of Western Bengal, I have occa¬ 
sionally met with it in small quantities. In the district of Singhbhum, south of the station 
of Chaibassa, it occurs in beds of a white limestone. 
In the Madras presidency, in the eastern part of the Kadapa District, a beautiful ser- 
pentinous marble is said to occur, but it has not been much used hitherto. 
Dykes of serpentine, possibly the result of alteration of some original igneous rock, 
occur most uncommonly in the tertiary sandstones of the Andaman and Nicobar Islands. 
Some of the purer varieties might, if obtainable in large blocks, be used for ornamental 
purposes. A black variety streaked with green, which ■ occurs at the head of Port Blair, 
particularly attracted my attention. So far as I know, no attempt has been made to work it. 
Serpentine is said to be found in parts of Upper Burma, where it is worked and exported 
to China. 
Potstones .—Chloritic schists, passing, on the one hand, into talcose, and, on the other, 
into serpentinous rocks, occur not uncommonly in the-sub-metamorphic and somewhat less 
frequently in the metamorphic series. 
In buildings the varieties'of this material have only been used on a small scale for 
ornamental purposes, for which some of them, as being tough and at the same time easily 
carved, are particularly suited. More extensively they are used in the manufacture of altars, 
idols, plates and bowls. 
In the southern part of Manbhum, on the frontiers of Singhbhum, there are numerous 
workings, which generally take the form of narrow mines which are deserted during 
the rains. From these mines a considerable quantity of stone is annually extracted; the 
blocks are roughly dressed to the shape required, be it for Lingam, plate or bowl. They are 
then fixed in a rude lathe and cut into form and given a smooth surface. When finished, 
they are carted off to Burdwan, where they are in great demand, and a portion are sent on to 
Calcutta for sale. 
In the neighbourhood of Gya too, there are many large mines and quarries of this stone, 
which supply a considerable trade in idols and utensils. 
One class of the varieties used stands fire well, while the other does not. The former is 
of course the most esteemed by the natives. The crackiug of the latter is probably due to 
the water of combination in the more chloritic varieties, which becomes released on the appli¬ 
cation of heat. 
